Reaction to comments of the reviewers
After rereading the paper with the comments of the reviewers in mind, we rewrote the whole paper, in
particular the results section and the discussion. We changed the research questions and they are more
focused now. Some results are therefore also deleted. We paid special attention to the parts considered to
be unclear by the reviewers. We hope the paper is clearer now.
Reviewer Salmon
Reviewer Salmon pointed at several unclarities and incorrect sentences (of which, we think, some are not
incorrect but unclear). We agree with most of his comments. Below I reply in more detail how we took care
of his comments.
…..
General
------------------------------------------------------------------------------Major Compulsory Revisions
The first sentence of the abstract is factually incorrect. Parents have not always been ambivalent toward
vaccination. What about the tremendous public support for the polio vaccines? These vaccines were
funded through public donations (March of Dimes) and the clinical trials were among (if the not the) largest
clinical trials ever conducted in the U.S. Public demand for a vaccine to prevent polio was enormous.
Although we agree with the reviewer’s remark that there is public support for polio vaccines, we
also think that there were always parents who were opponents of mass vaccination. We base
ourselves on several publications (see reference list). We understand that the acceptance of mass
vaccinations differ between diseases, with the lowest acceptance rate of vaccination against
disease perceived to be less serious. Therefore, we changed the first sentence in order to give a
more balanced picture of the acceptance of mass vaccination programs.
Abstract: Parents’ reported ambivalence toward large-scale vaccination programs
for childhood diseases may be related to their perception of the risks of side-effects
or safety of vaccination and the risk of contracting the disease.
Throughout the manuscript the term risk (appraisal of in the abstract and often perceived risk) – often the
authors seem to mean risk of disease. This should be specifically stated.
We agree with the reviewer that this is not clear. We used the words “risks related to vaccination”
on several places throughout the article meaning to be the risk of contracting the disease, residual
risk of contracting the disease after vaccination, risk of dying of disease, and the risk of side
effects. We explained this on page 5. However, we realize that we should explain this earlier and
should more clear about the term risk when we use it. Thus, we changed the wording in several
places in the article (e.g. the abstract). Sometimes we replaced these terms with safety (i.e. risk of
side effects) and effectiveness (residual risk on disease after vaccination).
Abstract: Parents’ reported ambivalence toward large-scale vaccination programs
for childhood diseases may be related to their perception of the risks of side-effects
or safety of vaccination and the risk of contracting the disease. The aim of this study
is to evaluate parents´ perceptions of their child’s risk of contracting Meningococcal
C infection and parents’ perceived control in preventing an infection in relation to
their evaluation of the safety, effectiveness and usefulness of vaccination
This seems to be a cross-sectional survey (this should be stated) and it is not clear if a sample of
participants was drawn or if all persons who came to the catch-up campaign were enrolled. If this was a
sample, was it a random sample? This should be clarified.
We agree that this could be clearer. We added some text on page 5.
The children and their parents were invited in the Ajax soccer stadium, the Arena in
Amsterdam. In this cross-sectional study a random sample of parents was invited for
a structured interview by one of the 30 interviewers after their children received the
vaccination. The interviewers had received a 30-minute training course by one of the
authors (L.H.) and an instruction sheet. If the child was accompanied by a couple,
the female of the couple was selected for the interview.
Throughout the paper the term “average” is used – is this the mean that is being referred to? This needs
to be clarified.
On places were we used the term “average” while meaning “the mean”, we changed or deleted
the wording.
It is not clear in the description of the letter and leaflet if the information provided was the same
information as was asked (i.e., did the leaflet provide estimates of the risks of contracting meningococci
and the mortality risk)?
No, the information provided was not the same as the information that was asked. As
stated on pages 5 and 6, no risk estimates were given in the leaflet. We did not change the
text, because we assume it is clear enough. We added some text about how risks were
represented.
Accompanying each invitational letter was a leaflet about the disease and the
vaccination. Enclosed with each invitational letter was an information leaflet with a
contact telephone number and website address for more information … It also
included (limited) information on possible side effects such as rises in temperature,
listlessness, headache, and effects related to the injection such as redness, swelling
and pain. No numeric probabilities were given, but risks were described in words.
Vaccination was free of charge.
The statistical analysis section is not clear. It sounds like multiple logistic regression analysis was done. If
so, specify what outcome variables were used (assuming multiple models) and what independent
variables were included. In presenting results, percentages would be very helpful, along with odds ratios
(if this was logistic regression analysis).
We rewrote the statistical analysis section.
Characterization and analysis by “realists” and “pessimists” should be described in the methods section.
We included this in the methods section.
Last sentence on page 10 – stating that religion and ethnicity made no difference suggests that the study
was able to determine causal relationships. This is not possible using this study design. Instead, the
authors should describe associations that are or are not associated.
The reviewer is right. This is unclear. This section is deleted because we decided that the paper
would be more clear and focused if we deleted analyses of differences between parents due to
ethnicity or religion.
The first paragraph of the Discussion and Conclusion section is too long and complicated. It is very difficult
to understand the points trying to be made.
When reading it again, we have to agree with the reviewer. We rewrote the complete discussion
and hope it is better now.
The point that only parents who decided to vaccinated their children were included in the sample is very
important and needs to be highlighted. It is buried rather deep in the paper.
We mentioned this in the discussion on page 11, and added some more explanation. However,
we do not think this is so important, because the uptake rate of this vaccination against
Meningococcal C was 95% (in correspondence with the mean uptake rate for vaccination against
childhood diseases). The population in our study can be considered to be a representative sample
of the Dutch population with children. Typically in the Netherlands, most of the few (5%!!) who did
not take their child for vaccination, have religious reasons (See Rumke and Visser, 2004).
------------------------------------------------------------------------------Minor Essential Revisions:
The last sentence of the results section in the abstract is too long and confusing.
We changed this
In the background section, perceived likelihood of being exposed to the disease should be included.
Perception of health risk (i.e., risks of disease) has been studied in the vaccine context (last sentence,
page 4).
We changed this.
Under research question (4) – when referring to differences between parents, are the authors intending to
examine differences in parents perceptions of these issues depending on education level, ethnicity or
religion?
Yes, we deleted this sentence as it is not the main research question.
For the questions included (page 6) – were exact numbers requested for numeric risk or were ranges
requested? Was this information provided to parents in the pamphlet?
Yes, exact numbers were asked and this information was not provided in the leaflet, and only
verbal descriptions (e.g. very low risk) were used. See also our reaction to another comment of
this reviewer above.
For question number 4 (top of page 7) – what was the exact wording?
We added an appendix with the questions.
Perceived control (page 7) – what were the actual questions (yes/no to what)? Were respondents given
specific examples of other preventive measures?
See appendix
How was education level defined into three categories (low, moderate and high)?
Educational level was asked in 3 categories. See appendix.
For perceived risks and actual risks (page 8) – it would be helpful to report ranges as well as means.
Although we agree with the reviewer, we deleted these results because we changed the research
questions to be more focused.
First paragraph, page 12, “it has been argued that the language of risk might not be the best way to
convince parents”. Is it the intention of the authors to suggest that the intent of risk communication is to
“convince”? Rather, risk communications, many would argue, should be intended to educate parents to
make informed decisions.
We agree with the reviewer that this phrase is not clear. We deleted this sentence (as the
complete discussion is rewritten).
Two sentences later, “this group” needs to be defined
We changed it.
------------------------------------------------------------------------------Discretionary Revisions:
Delete “a” before “Meningococcal” in the title
We changed it.
Table 1 – how does Christian differ from Catholic and Protestant?
This is indeed not clear. This category is for people who do not consider them Catholic or
Protestant, but still Christian. We added the word ´other´.
Table 2 is very difficult to follow. Why are p values only <0.001 included? What about p values <0.05 to
>0.001?
We only indicated if differences were significant and if they were, they were significant at the level of p <
.001 (table 2).
Reviewer Elliman
This report describes the views of an unrepresentative group (the authors point this out themselves) of
parents of children who had had meningococcal C immunisation.
We disagree with this reviewer’s remark: the group we interviewed about meningococcal c
vaccination is not unrepresentative: almost all parents in the Netherlands have their child
vaccinated (uptake over 95%) and we interviewed a representative sample of these parents and
thus a representative sample of parents in the Netherlands. Thus, it is true that the parents
interviewed had their children vaccinated, but this is true for nearly all parents of children in the
Netherlands. We added some sentences in the discussion to explain this more clearly.
The authors do not provide the questionnaire they used, but say it only took 5-10 minutes to administer.
The impression is that this was not an in-depth study.
Indeed, it was not an in-depth study, but it was an explorative study with a large representative
sample with relevant results. It was, however, enough time to ask several relevant questions. We
do not understand why it is a problem that this study was not an in-depth one (how many
questions are needed to qualify as an in-depth study?), but we also think that it would be useful to
further examine the results in another study. The last remark of our discussion is about this.
Questionnaire items are now provided in the appendix.
As the authors have only given the views of 'immunising' mothers, it is not possible to draw any
conclusions as to how this might influence their 'immunising' behaviour.
We do not draw conclusions about immunising behaviour. We discussed that some attitudes of
parents might be problematic and that the same negative ideas about vaccination found in other
studies among parents who decide not to vaccinate their children.
Based on our reaction to this comment and the previous comment, we disagree with this reviewer
that our study was scientifically unsound.
Little of the information is new.
We do not understand what this reviewer means with "little of the information is new"? We
explained in the introduction what our study adds to the existing literature.
For instance:
Perceived control and perceived vulnerability has been shown to be of importance
for the perception of health risks and decisions concerning one’s health, but have
not been studied in vaccination behaviour.